package com.example.kotlin

class LearnKotlin {

}

var content:String?="hello"

fun main() {
    println("hello world")

    var p = Person()
    p.name = "小明"
    p.eat()

    var s1 = Student()
    s1.name = "小郑"
    s1.age = 12
    s1.doHomework()

    if (content != null){
        printUpperCase()
    }
}

fun printUpperCase(){
    val upperCase = content!!.uppercase()
    println(upperCase)
}